applied patch from Malcolm Tredinnick fixing errata E20 concerning

* valid.c TODO: applied patch from Malcolm Tredinnick fixing errata
  E20 concerning NMTOKENS and co. validation #153722
* result/VC/AttributeNmtokens test/VC/AttributeNmtokens
  test/VCM/AttributeNmtokens.xml: also added tests from Malcolm
Daniel
diff --git a/valid.c b/valid.c
index f1e5007..6b2d08e 100644
--- a/valid.c
+++ b/valid.c
@@ -3306,8 +3306,9 @@
 	cur += len;
     }
 
-    while (IS_BLANK(val)) {
-	while (IS_BLANK(val)) {
+    /* Should not test IS_BLANK(val) here -- see erratum E20*/
+    while (val == 0x20) {
+	while (val == 0x20) {
 	    val = xmlStringCurrentChar(NULL, cur, &len);
 	    cur += len;
 	}
@@ -3418,8 +3419,9 @@
 	cur += len;
     }
 
-    while (IS_BLANK(val)) {
-	while (IS_BLANK(val)) {
+    /* Should not test IS_BLANK(val) here -- see erratum E20*/
+    while (val == 0x20) {
+	while (val == 0x20) {
 	    val = xmlStringCurrentChar(NULL, cur, &len);
 	    cur += len;
 	}